FIG. 8 illustrates an example of a double cavity toroidal continuously variable transmission which is used, for example, as a transmission for an automobile vehicle. Here, in FIG. 8, sectional positions of a pair of cavities are mutually deviated in the rotational direction by 90 degrees. As illustrated in the drawing, a toroidal continuously variable transmission 1 includes a pair of input discs 2a, 2b being outer discs, an integrated output disc 3 being an inner disc, and a plurality of power rollers 4, 4. The pair of input discs 2a, 2b is rotatably connected as being synchronized in a mutually coaxial fashion via an input shaft 5 being a rotary shaft. Further, the output disc 3 is supported between both of the input discs 2a, 2b coaxially to both of the input discs 2a, 2b as being rotatable relatively to the both of the input discs 2a, 2b. Further, the power rollers 4, 4 are sandwiched by two or more respectively between axial-direction two-side surfaces of the output disc 3 and axial-direction one-side surfaces of both of the input discs 2a, 2b. Then, the respective power rollers 4, 4 transmit power from both of the input discs 2a, 2b to the output disc 3 while being rotated in accordance with rotation of both of the input discs 2a, 2b. 
Both end portions (hereinafter, also called small end surfaces) in the axial direction of the output disc 3 are rotatably supported by a pair of ball bearings 6, 6 respectively being a thrust angular type. Accordingly, support posts 8a, 8b fixedly arranged at an inner surface of the casing 7 are connected by a circular retaining ring 9 which is a member fixed to the casing inner surface. The respective support posts 8a, 8b are for supporting support plates 11a, 11b which support both end portions of trunnions 10, 10 being support members to rotatably support the respective power rollers 4, 4 and are coaxially arranged to each other at the radially-opposite sides as sandwiching the input shaft 5. In this structure, a pair of the support posts 8a, 8b is connected by the retaining ring 9 and the input shaft 5 is inserted to the inside of the retaining ring 9.
Then, the ball bearings 6, 6 are arranged between the retaining rings 9, 9 which are arranged at the respective cavities and axial-direction two-end surfaces of the output disc 3, that is, portions being closer to the inner diameter side than output side surfaces 12, 12 arranged at the two-side surfaces of the output disc 3. Short cylinder-shaped projecting stripe portions 14, 14 are formed over the entire peripheries at portions being close to the inner diameter side of outer surfaces (side faces being at mutually opposite sides) of a pair of thrust bearing rings 13a, 13b which structures the respective ball bearings 6, 6. Then, positioning of the respective ball bearings 6, 6 in the radial direction is performed by internally fitting the projecting strip portions 14, 14 to the retaining rings 9, 9 and the end portions of the output disc 3. Further, positioning of the respective ball bearings 6, 6 in the axial direction is performed by sandwiching shim plates 15, 15 respectively between one outer side surface of each of the thrust bearing rings 13a, 13a and the retaining rings 9, 9. Further, in this state, desired preliminary pressure is exerted to the ball bearings 6, 6. The output disc 3 is rotatably supported between pairs of the support posts 8a, 8b which are arranged by a pair in each cavity in a state that positioning is performed in the radial direction and the axial direction.
As described above, there have been a variety of structures depending on an integrated output disc (for example, see Patent Literatures 1 to 3).